Intra-cellular sensors offer a powerful tool for understanding the mechanisms within a cell. Such sensors can detect the presence or concentration of an analyte within the cell, and when multiple sensors are distributed within the interior of the cell, the presence of analytes in relation to different cellular organelles and the cell membrane can be better understood.
Sensors can be introduced into cells using a variety of techniques, however, in many cases, the sensor becomes encapsulated within an endosome of a cell. In the endosome, the sensor is sequestered from the analytes in the cytosol, rendering the sensor ineffective for monitoring intracellular analytes or otherwise diminishing its sensitivity. In order to localize sensors in the cytosol of the cell, methods or compositions that allow the sensor to escape from the endosome into the cytosol of the cell would be highly desirable.